The St. Wenceslas Rotunda, first mentioned in the St. Wenceslas legend originating in the 13th century, was searched for by historians and archaeologists for centuries. It was located thanks to a comprehensive reconstruction of the building of Charles University's Faculty of Mathematics and Physics situated at Malostranské náměstí (the Lesser Town Square). The remnants of the rotunda were discovered on 3 February 2004 during the reconstruction works, by accident. Based on an engraving depicting the 1611 invasion of the Lesser Town of Prague by the Passau mercenaries, scholars had always assumed that the rotunda was situated within the western row of houses in the middle of the Lesser Town Square. The archaeological discovery proved that, in reality, it was situated more to the east. Historical sources claimed that the rotunda was torn down in 1683 while, in fact, its parts were incorporated in the foundations of a 'house of professions' built by the Jesuits.